Fixed wireless systems are currently employed for local telecommunication networks, such as the IONICA fixed radio access system. Known systems comprise an antenna and decoding means which are located within a subscriber's premises, for instance adjacent a telephone. The antenna receives the signal and provides a further signal by wire to a decoding means. Thus subscribers are connected to a telecommunications network by a radio link in place of the more traditional method of copper cable. Such fixed wireless access systems will be capable of delivering a wide range of access services from POTS, ISDN to broadband data. The radio transceivers at the subscribers premises communicate with a base station, which provides cellular coverage over, for example, a 5 km radius in urban environments. A typical base station will support 500-2000 subscribers. Each base station is connected to the standard PSTN switch via a conventional transmission link/network.
When a fixed wireless access telecommunications system is originally deployed, then a base station of a particular capacity will be installed to cover a particular area. The capabilities of the base station will be commensurate with the anticipated coverage and capacity requirement. Subscribers antennas will be mounted outside, for instance on a chimney and upon installation will be directed towards the nearest base station or repeater antenna (any future reference to a base station shall be taken to include a repeater). In order to meet the capacity demand, within an available frequency band allocation, fixed wireless access systems divide a geographic area to be covered into cells. At the centre of each cell is a base station through which the subscribers stations communicate; the distance between the cells being determined such that co-channel interference is maintained at a tolerable level.
Obstacles in a signal path, such as buildings in built-up areas and hills in rural areas, act as signal scatterers and can cause signalling problems. These scattered signals interact and their resultant signal at a receiving antenna is subject to deep and rapid fading and the signal envelope often follows a Rayleigh distribution over short distances, especially in heavily cluttered regions. Since the various components arrive from different directions, there is also a Doppler spread in the received spectrum.
Correct alignment and installation of a fixed wireless access subscriber terminal towards a geographically proximate base station is essential for the correct performance of the network. At present, the lack of subscriber location precision has resulted in subscribers `firing` across proximate base stations to more distant base stations. This causes a higher level of interference to be experienced than optimum alignment would provide. Presently, as operators of fixed wireless access systems are deploying their equipment into an already crowded telecommunications marketplace, to enable them to operate at sufficient competitive levels there must be a high rate of deployment of subscribers equipment. Obviously, such deployment must not be time consuming for installation engineers. Presently, problems have been experienced in the installation of subscribers equipment, and more particularly, in the mounting of the antennas required to transfer radio signals with a base station; the subscribers antenna must be oriented towards the base station to enable the signals to be of sufficient strength. In particular the installation engineers have reported difficulties in determining the location of the subscribers premises with respect to a proximate base station, where the techniques employed have been based on traditional cell planning and data base methods.